The subject matter disclosed herein relates to a steam turbine nozzle assembly, or diaphragm stage. Specifically, the subject matter disclosed herein relates to a steam turbine diaphragm stage having a self-aligning flow splitter.
Steam turbine designs include static nozzle (or, airfoil) assemblies that direct the flow of a working fluid (e.g., steam) into turbine buckets (or, airfoils) connected to a rotating rotor. A complete assembly of nozzle segments is commonly referred to as a diaphragm stage, or nozzle assembly, of the steam turbine. Turbine diaphragms are conventionally assembled in two halves around the rotor, creating a horizontal joint. Some sections of conventional steam turbines have a double-flow design in which half of the fluid flow is provided to the left-hand portion of the diaphragm, and the other half of the fluid flow is provided to the right-hand portion of the diaphragm. The diaphragm stage that splits the flow (providing fluid to the left and right portions) is called a flow splitter (or, tub) stage.
Conventional flow splitter stages include left and right nozzle assemblies bolted at a flange. Due to the bolted designs and the limited accessibility associated with these designs, electron beam welding (or another deep penetration weld) is used to attach the flow splitter stage to left and right nozzle assemblies. Additionally, the size of the flange, bolt head and nut causes significant windage that may negatively affect turbine performance. These conventional designs and the welds associated with those designs may involve costly labor and cause distortion in the left and right nozzle assemblies, thereby diminishing the performance of the steam turbine.